My s/o talks weird to devices... she pitches her voice oddly and it's hard for even me to understand her. Devices do not understand. Maybe record yourself or ask someone to listen to you talking to a device and see if you're unconsciously changing delivery?

Voice assistants are much better with lower voices than higher ones (especially Alexa). One tip is to deepen your voice, that might help.

My voice is extremely, unusually deep. I actually suspect that is the problem itself, it is deep enough that it doesn’t even register as speech to these systems.